amp gage shows discharge

[SDE]

Farmall 400 was a positive ground system with a 12 volt generator. I changed it to negative ground. Polarized the system and turned the key and it started but died as soon as the key returned to the run position. I removed the dash and swapped the wires on the amp gage from one terminal to the other. It now starts and runs. At rest the battery shows 12.5 volts. With the engine running, the multimeter reading is over 12.5 but is so erratic that I am going to assume it must be charging. I think there were two wires on each terminal of the gage. Can you tell me which wire or wires I need to swap back? TY Steve

 

[used red MN]

Farmall 400 was a positive ground system with a 12 volt generator. I changed it to negative ground. Polarized the system and turned the key and it started but died as soon as the key returned to the run position. I removed the dash and swapped the wires on the amp gage from one terminal to the other. It now starts and runs. At rest the battery shows 12.5 volts. With the engine running, the multimeter reading is over 12.5 but is so erratic that I am going to assume it must be charging. I think there were two wires on each terminal of the gage. Can you tell me which wire or wires I need to swap back? TY Steve

In my world if you want to the ammeter to read all current loads and then the compensation the generator is adding as charge the wire that supplies battery voltage to the ammeter needs to be on one terminal of the ammeter by it self. All others loads and the wire that brings the charging current in from the regulator go on the opposite terminal. The Bat terminal on the regulator will be that circuit.

 

[SDE]

Thank you. I was hoping that I could get the wiring correct on my first attempt.